Less than 2 percent of the scats contained human food, he said, and only 1 percent had pet remains.

Today coyotes live in every park across the Chicago region, Gehrt says, even in the downtown area.

When he first started radio collaring and tracking the animals six years ago, he thought they'd avoid busy city streets and stay within park boundariesthey didn't.

A young female coyote once led Gehrt 20 miles (32 kilometers) through five different cities within a six-hour period.

"This was over by O'Hare [International Airport]," he said. "It was extremely developed and [there was] tons of traffic. She was crossing roads. I realized that night I had underestimated their ability to move across that."

As part of an agreement with Chicago city government, Gehrt puts tracking collars on captured "nuisance" coyotes and then releases them on the very edge of the urban sprawl.

"Basically they have a choice," he said of the coyotes. "If they take a left, they can go out into rural areas. If they take a right, they're going to head back into the city.

"In every single case they've always chosen to go back into the city, so those particular coyotes view this urban area as a favorable kind of habitat."

Gehrt's research has shown the survival rate of urban coyotes is twice that of their rural counterparts.

Coyote-Wolf Hybrids?

Already the relatively recent eastern coyote population is showing signs of genetic divergence from their cousins that stayed out West.

In 2001 DNA samples from a hundred coyotes killed by hunters in Maine showed only four had ancestry similar to western coyotes.

"What that indicates is a degree of isolation between the two populations," said the study's co-author, Walter Jakubas with the Maine Department of Inland Fisheries and Wildlife.

"Our eastern coyotes are kind of becoming their own distinct population, if you will."

What's more, 22 of the 100 coyotes had more than 5 percent wolf ancestry, and 5 had more than 30 percent wolf genes.

Jakubas believes the hybridization occurred when western coyotes began migrating east but took a detour into Canada, where they mated with wolves.

These hybrids now live in Maine, New York, and New Jersey.

Mating between eastern Canadian wolves, red wolves, and coyotes is possible, he said, because they share a common ancestor.

While coyotes help control populations of geese, rodents, and white tail deer, in many parts of the country they're still considered pests.

"For better or worse, most people view coyotes as trouble makers," said Jakubas. "Some of your western states do not even protect them as a wildlife species. They're just considered vermin. You can do anything you want to them."

Coyotes have been hunted and trapped for more than 200 years, and the largest killer is the U.S. government.